CVE-2026-42771
CVE-2026-42771 is a medium-severity vulnerability in Openssl with a CVSS 3.x base score of 6.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.
Key facts
- Severity: Medium (CVSS 3.x base score 6.2)
- EPSS exploit prediction: 0% (9th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-35488
- Weakness: CWE-125
- Affected product: Openssl
- Published:
- Last modified:
Description
Issue summary: When the X509_VERIFY_PARAM_set1_email is called by an application to validate a crafted e-mail address, such as during S/MIME message validation, an out of bounds read can happen. Impact summary: This out of bounds read will not directly exfiltrate the data read to the attacker so the most likely result is a crash and a Denial of Service. An internal helper function called from X509_VERIFY_PARAM_[set|add]_email() used a wrong length when validating the local part of an email address. This could cause the 64 octet limit on the local part of an email address to be not enforced, or cause an out of bound read and potentially a crash. The bug is reachable via S-MIME validation with a crafted From: address supplied in an email message that can potentially cause a crash. No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.
Frequently asked questions
- What is CVE-2026-42771?
- Issue summary: When the X509_VERIFY_PARAM_set1_email is called by an application to validate a crafted e-mail address, such as during S/MIME message validation, an out of bounds read can happen. Impact summary: This out of bounds read will not directly exfiltrate the data read to the attacker so the most likely result is a crash and a Denial of Service. An internal helper function called from X509_VERIFY_PARAM_[set|add]_email() used a wrong length when validating the local part of an email address. This could cause the 64 octet limit on the local part of an email address to be not enforced, or cause an out of bound read and potentially a crash. The bug is reachable via S-MIME validation with a crafted From: address supplied in an email message that can potentially cause a crash. No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.
- How severe is CVE-2026-42771?
- CVE-2026-42771 has a CVSS 3.x base score of 6.2, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2026-42771 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-42771?
- CVE-2026-42771 affects Openssl. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-42771?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-42771 have an EU (EUVD) identifier?
- Yes. CVE-2026-42771 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35488.
- When was CVE-2026-42771 published?
- CVE-2026-42771 was published on 2026-06-09 and last updated on 2026-06-17.
References
- https://github.com/openssl/openssl/commit/6cd187689f8180c1f8a3acde21f88190c4a20de7
- https://openssl-library.org/news/secadv/20260609.txt
Affected products (1)
- cpe:2.3:a:openssl:openssl:4.0.0:-:*:*:*:*:*:*
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